The present invention relates generally to plastic fasteners and more particularly to a plastic fastener that is well-suited for shoe-lasting applications.
Shoe-lasting is a technique commonly employed in the manufacture of footwear for working a shoe upper into its proper form prior to the attachment of a sole thereto. Typically, shoe-lasting comprises placing an unworked shoe upper over a shoe last, i.e. , a mandrel having a shape similar to a shoe-tree, and then heating and pulling the shoe upper around the shoe last until the upper conforms generally to the shape of the shoe last.
For shoes of the type that are provided with shoelace eyelets, the above-described technique can pose a problem since the tensioning of the shoe upper around the shoe last can cause the spacing between opposing eyelets on the upper to deviate from what it should be. One approach that has been used to maintain the proper spacing between opposing eyelets on the upper has been to tie together the eyelets with string or the like. Typically, this tying operation is performed with a specifically-designed machine. However, machines of this type have not been made for several years and are, therefore, quite old. In addition, such machines are rather difficult and costly to maintain and use.
Another approach that has been used to maintain the proper spacing between opposing eyelets of a shoe upper during shoe-lasting has been to couple together pairs of opposing eyelets on the upper using plastic fasteners of the type sold by Avery Dennison under the trademark SHD T-End Fasteners. Such fasteners are typically unitary structures each comprising an elongated filament terminating at opposing ends in a cross-bar. To attach the fastener to a shoe upper, one of the cross-bars is inserted through a pair of opposing eyelets on the shoe upper, the other cross-bar not being inserted through either of the eyelets. The cross-bars are appropriately sized so that the fastener cannot easily be pulled through either of the eyelets.
The aforementioned fastener, however, has not been found to be entirely satisfactory in shoe-lasting applications. This is because, where the eyelets of the upper are relatively large compared to the size of the cross-bars, the magnitude of the force used to pull the upper over the shoe-last is often so great as to cause at least one of the cross-bars to be bent inwardly and then pulled through its respective eyelet.